1. Field of the Invention (Technical Field)
The present invention relates to electronics packaging devices and methods.
2. Background Art
Electrical circuits and components are typically formed or placed on dielectric substrates. Substrates such as silicon, ceramic, FR-4, plastic, and Kapton form a stable, flat, rigid platform and thus reduce the complexity of forming or assembling complex electrical circuits. When the substrate is FR-4 or a similar glass-epoxy dielectric, the term xe2x80x9ccircuit-boardxe2x80x9d is commonly used for the assembly consisting of many electrical components affixed to the substrate and interconnected electrically by traces on the surface of the substrate. When moderately flexible dielectric substrates like Kapton are used in a similar way, the resulting assembly is often referred to as a xe2x80x9cflex circuit.xe2x80x9d For a silicon or similar semiconductor substrate, electrical circuits are etched directly onto the surface of a rigid semiconductor substrate, and the terms xe2x80x9cwaferxe2x80x9d and xe2x80x9cdiexe2x80x9d commonly apply to the resulting assembly. Electrical components are typically placed on the surface and then soldered in-place to conducting traces usually etched in the surface of the substrate. Finally, these substrates with circuits on board are typically mounted in an enclosure via fasteners through the substrate or direct bonding of the substrate to an enclosure or other similar means which offers mechanical protection.
As a result of the general use of these substrates, however, known methods of packaging electrical circuits create many undesirable constraints for applications where space, weight, and shape are fundamentally important or where it is desirable to have the electronic package change shape, dimension, size, and/or volume during installation or use. For example, existing circuit assemblies (circuit boards, wafers, and flex circuits, hereafter collectively referred to as circuit-boards) cannot be compressed, distended, twisted, or flexed into any desired shape (flex circuits offer a very limited range of flexure only) in order to conform to the location into which they must be placed or to ease their installation. The state of the art for flex circuits is represented by U.S. Pat. Nos. 4,435,740; 5,014,162; 5,220,488; and 5,241,454.
In addition, circuit-boards must be coated after final circuit assembly with a xe2x80x9cconformal coatxe2x80x9d to protect the assembly from moisture, etc. and to electrically isolate components and traces on the assembly. A circuit-board provides no seal for the place where it is installed; if a seal is required, it is incorporated as a separate part of the place where the circuit-board is installed.
The present invention removes these constraints while it provides additional functionality and advantages for many applications. The present invention further accomplishes the functionality of existing circuit-boards without introducing a substrate. Since it uses no substrate, it does not constrain circuit elements to any plane or surface, and it is extremely flexible, stretchable, distensible, and compressible.
There is an existing commercial and industrial need to prevent harsh environmental factors (such as water/humidity, corrosive solutions, oils, etc.) from passing through electrical connectors into sensitive electrical equipment. Some high-end military standard connectors, like MIL-C-38999 connectors, incorporate silicone rubber interfacial seals to address this market need. Many standard off-the-shelf connectors do not incorporate such seals except as a custom feature or option. Sometimes the need for such seals is only discovered after electrical equipment is sold and used by the consumer in the real-world, and the manufacturer must then retrofit field units and modify units in production to add a seal, usually by changing out connectors. The state of the art for such seals is represented by U.S. Pat. Nos. 2,450,528; 2,451,516; 3,004,170; 4,629,269; and 4,993,964.
There is a similar, and often simultaneous, need for methods and products that filter or attenuate electrical noise, transients, and other disturbances on electrical conductors passing through electrical connectors. There are a wide variety of existing devices to serve this need. Existing devices fall into two basic categories: 1) filtering/transient limiting devices that are added to existing/ordinary-unfiltered connectors; 2) filtering/transient limiting devices that are only applicable for use with special connectors designed to accept them.
Prior art for devices of the add-on sort include U.S. Pat. Nos. 5,181,859 and 5,290,191 as well as 5,183,698 and 4,979,904. Prior art for devices of the second category (where the devices are integral parts of special connectors or are where the device is a special connector) include U.S. Pat. Nos. 5,194,010; 5,149,274; 5,134,252; 5,092,788; 4,954,089; 4,820,174; 4,729,743; 4,703,984; 4,440,463; 4,407,552; 4,362,350; 4,056,299; 3,905,013; 3,852,700; 3,825,874; 3,780,352; 3,670,292; 3,569,915; and 3,086,188.
The above devices include drawings of parts that xe2x80x9clookxe2x80x9d similar to the present invention to a casual observer (a bathtub drain cover shares this same look). Inspection of these references reveals that many of the look-alike parts are simply solid metal foils (e.g., variations of the common bathtub drain cover) that act as ground paths for electrical energy, so there is no packaging of electrical parts at all. The remainder of the look-alike parts all share a common thread: they use substrates as their basic design element. None discloses or suggests the possibility of an insulating elastomeric suspension system, nor the combination of an electrical packaging method and an environmental seal method, nor the use of an elastomeric substance to provide the xe2x80x9cspringinessxe2x80x9drequired to ensure a reliable reusable electrical contact between the part and the host connector. Furthermore, none realize the utility of a flexible, twistable, distensible, and compressible device that: (1) can accommodate variations in the host connector (such as pin locations, shell diameter, mating tolerances) for an improved fit; (2) eases the installation/removal process since the device can readily change shape as required during the process to minimize insertion and removal forces; and (3) survives large temporary pin misalignments (which commonly occur in the real-world due to severe shock or vibration or other trauma to the connector) without degradation of the contacts, seal, or other features.
Therefore, none of the known existing devices provide the capability to simply retrofit or modify existing (ordinary) electrical connectors to obtain the desired filtering or transient attenuation and at the same time add (or preserve their existing) environmental seal within the connector. Few existing devices provide the xe2x80x9cadd-onxe2x80x9d capability, none provide the xe2x80x9cadd-onxe2x80x9dcapability for connectors with common pin misalignments, and none provide (or preserve) the seal capability. None of the known xe2x80x9cadd-onxe2x80x9ddevices can adapt to the range of real-world variations and severe treatment encountered in existing connectors, such as misaligned pins, connector manufacturer-to-manufacturer variations, and severe temporary pin displacement caused by vibration, mechanical shock, or other connector trauma. For example, all of the xe2x80x9cadd-onxe2x80x9d devices use either a tight press-fit connection or a spring-finger connection to the connector pins. In the press-fit case, even slight pin misalignment will prevent installation of the device, or will damage the device if it occurs after installation. The spring-finger devices use xe2x80x9cspringyxe2x80x9d metals like BeCu, which by nature are easily permanently deformed (or xe2x80x9csprungxe2x80x9d in layman""s terms) once bent beyond a narrow operating range, as when a pin is temporarily bent out of position by shock or vibration, or when the device is installed onto misaligned, out of tolerance, or out of place pinb.
The present invention is of a device and method for suspending, interconnecting, and protecting circuitry comprising: an electrically and mechanically insulative body that changes shape and dimension when subjected to external forces; and circuitry suspended by the body and comprising electrical interconnects permitting components of the circuitry to move with respect to each is other as the body changes shape. In the preferred embodiment, the circuitry may be suspended within and/or on the body and the electrical interconnects are provided with slack or stretchable conductors. The body may comprise one or more openings therein having a conductor protruding into the opening from the body, such as a contact for making electrical connection to an external conductor inserted into the opening, and the body exerts compressive forces to push the contact against the external conductor. The body may also comprise one or more conductors protruding from an edge of the body, such as a contact for making electrical connection to an external conductor touching the edge, wherein the body exerts compressive forces to push the contact against the external conductor. The body preferably changes shape and dimension by being flexible, distensible, and compressible. It may be an elastomer, such as silicone, RTV silicone, heat-cured silicone, two-part silicone, latex, and rubber, or one or more materials selected from the group consisting of clays, gums, and foam rubbers.
The invention is also of a device and method for adding and connecting circuitry to an electrical connector, comprising: an electrically and mechanically insulative body that changes shape and dimension so that the device fits snugly about or within at least one coupling; circuitry suspended by the body and comprising electrical interconnects permitting components of the circuitry to move with respect to each other as the body changes shape; and contacts interconnected with the circuitry and protruding from the body for making electrical connection to at least one coupling. In the preferred embodiment, the body, when the device fits snugly about or within at least one coupling, creates an environmental seal preventing the passage of dust, fluids, gases, and other contaminants through the connector, the body exerts compressive forces on the contact to push the contact against at least one coupling, and the body further comprises at least one opening for fitting around a pin, wherein the diameter of the opening is smaller than the diameter of the pin when the device is not engaged to the pin, but expands to a diameter substantially equal to the diameter of the pin when the device is engaged to the pin. The circuitry may be suspended within or on the body. The electrical interconnects may include slack or stretchable conductors. The body changes shape and dimension by being flexible, distensible, and compressible, and may be an elastomer, such as silicone, RTV silicone, heat-cured silicone, two-part silicone, latex and rubber, or one or more materials such as clays, gums, and foam rubbers. The contacts preferably shift position due to the changes in the body to accommodate out of alignment couplings. The diameter of the body is preferably approximately 5% to 15% greater than the inner diameter of the connector. The contacts are preferably made of conductive wire or ribbon. The device may comprise external contacts disposed on an edge of the body, wherein at least one of the external contacts connects the circuitry to an outer shell of the connector. The circuitry may comprise electrical components selected from the group consisting of capacitors, resistors, MOVs, diodes, fuses, antifuses, shorting blocks, inductors, active electronic components, and any combination thereof. The device may thus be created with circuitry so as to filter electromagnetic interference. Or, the circuitry may comprise a network of ground buses electrically connecting a plurality of chip capacitors to an outer shell of the connector, each of the chip capacitors being electrically connected to one of the contacts. Alternatively, the circuitry may comprise electrical transient limiting circuitry.
A primary object of the present invention is to provide a means to package and interconnect electronic components using a mechanically and electrically insulative body to suspend the components and interconnects in such a way that they are free to move with respect to each other without degradation in performance as the shape, dimension, size, and/or volume of the body change during installation and use of the invention.
Another object of the present invention is to provide electrical interconnections suspended within the insulative body with sufficient slack and malleability to accommodate three-dimensional movement of individual components and contacts without functional degradation.
A further object of the present invention is to exploit a change in shape resulting from normal installation or use which allows it to perform important functions peripheral to the main electrical purpose, such as environmental sealing and/or enabling electrical contacts.
Another object of the present invention is to provide to an electrical connector an electrical device which filters or attenuates electrical noise, transients, and other disturbances and which simultaneously acts as an environmental seal.
A primary advantage of the present invention is that its body can be compressed, distended, deformed, and flexed during use without degrading its electrical functionality.
An additional advantage of the present invention is that it can adapt to a wide range of real-world conditions, such as misaligned connector pins, manufacturer variations, severe temporary pin displacement, and other trauma.
Another advantage of the present invention is that it provides the functionality of existing circuit-boards without introducing a substrate or wafer.
Yet another advantage of the present invention is that connectors both in the field and under manufacture may be easily modified to provide an environmental seal and an electrical functionality, such as transient filtering.
Still another advantage of the present invention is that its body may be constructed using an optically clear or translucent suspension material to assist in installation or to allow viewing of components within or behind the body.
Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.